Structure of Blood Vessels- 1

Question 1

Left Ventricle
Function:
Mean pressure:
Structural features:

Answer 1

Function: pump
Mean pressure: 95 mmHg
Structural features thick muscular walls, inlet & outlet valves

Question 2

Large arteries
Function:
Structural features:

Answer 2

Function: Conducting, dampen flow

Structural features: elastic fibres

Question 3

Medium-sized arteries
Function:
Mean pressure:
Structural features

Answer 3

Function: distributing, push blood to areas of demand

Mean pressure: 95-85 mmHg

Structural features: muscular walls to control diameter + CT for strength

Question 4

Arterioles, metarterioles, precapillary sphincters
Function:
Mean pressure:
Structural features

Answer 4

Function: control pressure flow
Mean pressure: 85-35
Structural features: smooth muscle to control diameter, little CT

Question 5

Capillaries
Function:
Mean pressure:
Structural features:

Answer 5

Function: slowed flow for gas/nutrient exchange
Mean pressure: 35-15
Structural features: endothelium, no muscle or CT

Question 6

Venules
Function:
Mean pressure:
Structural features:

Answer 6

Function: collecting vessels (small veins)
Mean pressure: 15-0
Structural features: thin walled, large diameter

Question 7

Veins
Mean Pressure:
Structural Features:

Answer 7

Mean Pressure: Low

Structural Features: Thin walled, variable structure, valves to assist return

Question 8

Right Atrium
Mean Pressure:
Structural Features:

Answer 8

Mean Pressure: 0-2

Structural Features: Thin, muscular walls

Question 9

The collecting system makes up __% of Blood volume

Answer 9

70%

Question 10

Elastic arteries

Answer 10

The aorta and pulmonary arteries, which occur jsut downstream of the ventricles.
They fuction to store blood during ‘Ventricular ejection’ or systole, then recoil during ventricular filling (diastle), to ensure steady blood flow from the heart.

Question 11

Elastic Arteries:

Tunica Adventitia

Answer 11

Usual collagen(restraint) and elastic fibres, small blood vessels “vasavasorum” and autonomic nerves

Question 12

Elastic Arteries:

Tunica Media

Answer 12

Well defined. Many lamellar units (50-60 in aorta). Each unit is made up of an elastic lamina, smooth muscle and collagen fibres. These run mainly in a circular orientation around the vessel

**smooth muscle has little effect due to large lumen

Question 13

Elastic Arteries:

Tunica Intima

Answer 13

Well defined. Thicker than in muscular arteries (up to 20% vessel wall), and contains longitudinal elastin fibres in the subendothelial CT. Run in a circular orientation around the vessel
IEL present but indistinguidable

Question 14

IEL and EEL of elastic arteries

Answer 14

Internal Elastic lamina: present but indistinguishable from elastic laminae of media (in TI)

External Elastic laminae: between media and adventitia

Question 15

Muscular Arteries: Tunica Intima

Answer 15

1) Endothelium
2) BM of endothelium
3) Subendothelium CT
4) A thick distinctive IEL. Smooth in life but with longitudinal folds after death

Question 16

Muscular Arteries: Tunica Media

Answer 16

Middle and thickest coat.

Smooth muscle fibres control vessel diameter.
Elastic fibres gives resiliency.
Collagen fibres limit expansion to prevent rupture.

**outer margin sometimes includes a EEL, never as prominent as the IEL

Question 17

Muscular Arteries: Tunica Adventitia

Answer 17

Outermost coat. Usually only collagen and elastin fibres. Vasa vasorum to service the outer layers of the vessel wall (these usually only present in larger muscular arteries)

Question 18

Arterial Disease: Atherosclerosis

Answer 18

Narrowing of arteries by plaque filling. Influenced by lifestyle

Question 19

Arterial Disease: Berry Anuerysm

Answer 19

Often found in the brain, upon rupture can lead to a stroke.

Bleeding into the media wall can result

Question 20

Arterial Disease: Dissecting Aneurysm

Answer 20

AAA: Abdominal Aortic Aneurysm
No way to predict
Weakness in wall, usually congenital, can lead to bleeding in the vessel wall
High risk, high % mortality

Question 21

Arterial Disease: Hypertension

Answer 21

Thickening of the vessel wall > high blood pressure

Normal BP: 120/80
Hypertension: >140/90

We see a narrowed lumen, duplication of IEL, thickening of the media (so SM increases) and thickening of the adventitia.

Very thick wall to lumen ratio.

Question 22

Arterioles

Answer 22

Smallest of the muscular arteris

• overall diameter of 100micrometers or less
• 3 or less SM layers in media
• Wall thickness = lumen

Question 23

Arterioles: Tunica Intima

Answer 23

endothelial cells overlying a basal lamina. IEL only present in larger arterioles

Question 24

Arterioles: Tunica Media

Answer 24

Thicker muscle coat in the media relative to the lumen then any other vessel. Therefore it is at the arterioles that the biggest pressure drop occurs, as variation in diameter has a huge effect on blood pressure.